Some days ago I got this amazing C64 breadbin, aesthetically in very good condition but with a faulty motherboard. Instead of the usual startup screen it showed an horrible “Out of memory error in 0” message error. This is a symptom of one or more bad RAM chips that need to be replaced.
These chips can be replaced with others as long as they have a RAS access time less then or equals to 200 ms. There are some similar models with these codes: 4164-2, MT4264-15, MT4264-20, HM4864P-2, M3764-15RS. I’ve found this good article where I found all the informations I was needed.
So I’ve bought a new set of RAM chips from a ebay seller and I armed myself with soldering iron and much of patience and started to desoldering and removing all the old chips.
Instead of soldering the new chips directly to the board, I soldered eight sockets. So in case of need it will be simple to replace the RAM chips in the future.
Then I put the new chips in the sockets, crossed my fingers and give power… and finally I saw the Basic screen. It works!!